Key Project Details

Description

Client

Architect

Mechanical Engineers

Lighting

Contractor

Project Value

$29 million. The project was jointly funded by Whangarei District Council & the New Zealand Transport Agency.

Duration

Design work was completed during 2011-2012 and Construction was completed in July 2013.

Challenges

The complexity of the project was heightened by the unique challenges presented by a bespoke design, including the integration of Structural, Geotechnical, Roading, Mechanical, Hydraulic and Lighting engineering for the Bascule Span and the supporting Piers.

An innovative Seismic Design Philosophy was required to investigate the separation of the Bascule Span from the Land Spans using 3-D finite element models in the analyses.

Features

Orthotropic Bascule Deck

Fish hook shaped Rolling Bascule J-Beams

Steel Ladder arrangement for Deck support with rigid connections to the Piers

Post-tensioning for the Pier, housing the hydraulic cylinders for supporting the Bascule Span

The Lower Hatea River Bridge, known locally as “Te Matau a Pohe” or the Fish Hook Bridge was completed in July 2013 and has enjoyed international recognition. The inspiration for the design of the Bridge was the shape of the traditional Maori fishing Hook.

The Steel Composite bridge is 265m long with nine 25m-long spans and two 20m-long end spans on each side of the central navigation channel of the Hatea River. The Bridge has a lifting Bascule span over the navigation channel which can be raised to allow vessels taller than 7.5m to transit the bridge.

The main deck consists of a Steel ladder arrangement with two longitudinal U-Girders and transoms creating a structural configuration for supporting the precast deck. Careful attention to detail allowed the fixed spans to be constructed quickly and efficiently and with precision.

The opening mechanism is based on a traditional rolling bascule, which consists of two steel J-shaped Beams supporting a light weight orthotropic road deck and two cantilever footways with an aluminium decking system. The J-Beams roll back on a Track and Rack mechanism and are raised by two Hydraulic cylinders with upper sections providing the balancing counterweight. As advantageous as the counterweights were, they presented a unique design problem. There were now enormous masses sitting high in the sky atop relatively slender and flexible J-beams. A finite element model was created to examine the natural frequency of the J-beams, which facilitated an assessment of vortex shedding. The model concluded that such vibrations would not be a significant issue.

The bascule span presented an interesting complication for the seismic design philosophy. Structurally, and mechanically, the best decision for the bascule span was to keep the two structures separate. The only solution was a complete air gap between the two structures.

The reliability of any moving bridge is a key to its success. If the bridge does not open when it is supposed to, or breaks down mid position then it quickly loses support from the local public. There have been no major issues with the operation of the bridge – something that is very rare for a bespoke, one off piece of machinery. The Client is very happy with the bridge’s performance and reliability.

The engineering excellence displayed in this project was the seamless integration of civil, structural, mechanical, electrical and hydraulic engineering into an architectural form to create a visually stunning and Iconic bridge, totally embraced by the local community.

“This architecturally designed Bridge fits seamlessly into the environment and it has a physical striking presence, without compromising on functionality and durability”
Judges Citation – NZ Concrete Society Awards

“I was completely blown away. Genuinely, it is the most beautifully built and assembled structure I’ve worked on. It’s just extraordinary”
Architect Martin Knight - Bridge Opening 2013

About Novare Design

Novare Design is a New Zealand based company of civil and structural engineers providing superior service nationally and throughout Asia and the Pacific. We pair innovation with experience to provide a professional yet personalised service for our clients needs. Our expertise includes the buildings, bridges, civil and infrastructure sectors. Novare Design has gained an enviable reputation for delivering solutions that exceed our client's expectations.

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Ph +64 4 939 9295

We provide local and international civil and structural design consultancy services to our clients, specialising in buildings, bridges, civil and infrastructure projects.

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